First off, Robert X. Cringely wrote a recent
column on the
comparative strengths of Linux and Windows. Here's a neat quote from the
article attributed to Linus Torvalds:

"Because the software is free,
there is no pressure to release it before it is really ready just to
achieve some sales target. Every version of Linux is declared to be
finished only when it is actually finished, which explains why it is so
solid. The other reason why free software is better is because the
personal reputation of the developer is attached to every release. If
you are making something to give away to the world, something that
represents to millions of users your philosophy of computing, you will
always make it the very best product you can make. That's the reason why
Linux is a
success."